The present invention relates to a contact structure of a switch for a compact electronic device used for a numeric keypad of a mobile telephone or the like, and more particularly, to a contact structure of a switch that is reduced in size and weight to the utmost and in which resources are saved to the utmost.
In a numeric keypad for a data inputting apparatus of OA equipment and AV equipment, a facsimile machine, and a telephone terminal apparatus including a mobile telephone as shown in FIG. 9, a keyboard switch using a substantially pan-like diaphragm made of metal or conductive material such as conductive plastic having spring characteristics is conventionally employed.
The keyboard switch will be explained while taking a mobile telephone shown in FIG. 9 as an example. A printed board 26 shown with a broken line is disposed in a case 27. Circle contacts 21 that are first contacts shown also with broken lines and diaphragms 25 shown with broken lines for bringing C-contacts or annular contacts that are second contacts into conduction are disposed in the printed board 26.
The case 27 is provided with keys 20 that can be pushed down, and if the key 20 is pushed down, a central portion of the diaphragm 25 is pushed and the circle contact 21 and the C-contact or annular contact are brought into conduction.
Details of a contact structure for a keyboard switch is disclosed in Japanese Patent Application Laid-open No. 5-74267. As shown in FIG. 10 for example, the circle contact 21 that is the first contact is disposed on the printed board 26, the circle contact 21 is surrounded by the C-contact 22 that is the second contact, the diaphragm 25 is placed on the C-contact 22 and fixed onto the printed board 26 through a single-sided adhesive sheet 28.
Then, as shown in FIG. 11, the central portion 25a of the diaphragm of the conductor is pushed and deformed by the key 20, and the circle contact 21 that is the first contact and the C-contact 22 that is the second contact are brought into conduction.
A shape of the contact may be annular instead of C-shape as disclosed in Japanese Patent Application Laid-open No. 3-230431. FIG. 12 schematically shows the circle contact 21 and the annular contact 22 of the printed board 26 accommodated in the case 27 of a mobile telephone shown in FIG. 9.
According to these conventional contact structures, however, the central portion of the conductive diaphragm is pushed and deformed to bring the central circle contact and the C-contact into conduction, and the conduction between the contacts is cut off by a restoring force of the diaphragm.
Therefore, it is necessary to make an outer shape of the diaphragm large in some degrees. Even if the central circle contact is made small, a size of the C-contact corresponds to that of an outer periphery of the diaphragm.
In recent compact electronic device such as a mobile telephone, a weight of an entire device is evaluated as an important index for carrying performance. Therefore, every part need be reduced in weight to achieve the weight reduction in gram.
Thus, size and weight reducing utmost method is required for a contact using metal material. A problem is how to reduce the weight while enhancing or maintaining the performance. On the other hand, it has become widely and increasingly valued in effectively using resources or recycle, and it is required to save metal such as gold that is rare metal.
It is an object of the present invention to provide a contact structure of a switch for a compact electronic device used for a numeric keypad of a mobile telephone or the like that can be reduced in size and weight to the utmost and in which resources can be saved to the utmost.
To achieve the above object, according to the present invention, there is provided a contact structure of a switch comprising a first contact, and one or more second contacts surrounding the first contact, wherein the second contacts are provided with one or more band-like contacts extending to the opposite side from the first contact.
The band-like contacts may extend radially with respect to a center of the first contact, or the band-like contacts may extend into fan-like shape with respect to a center of the first contact.
Since the one or more second contacts surrounding the first contact are provided with the one or more band-like contacts extending to the opposite side from the first contact, there is a merit that an area of the metal pattern portion of the second contact can be made smaller as compared with the prior art.
Further, if the band-like contacts extend radially with respect to a center of the first contact, there is a merit that a larger number of band-like contacts having smaller width can be disposed.
Further, if the band-like contacts extend into fan-like shape with respect to a center of the first contact, there is a merit that the area of the metal pattern portion of the second contact becomes wider as separating from the center of the first contact.
Further, the present invention provides a contact structure of a switch comprising a first contact, one or more second contacts surrounding the first contact, and a pan-like diaphragm comprising a conductor, wherein the second contacts are provided with one or more band-like contacts extending to the opposite side from the first contact, an outer periphery of the pan-like diaphragm is placed on the band-like contacts extending from the second contacts and brought into conduction with the band-like contacts, a center of the pan-like diaphragm is pushed down and bent, the center of the pan-like diaphragm is brought into contact with the first contact and into conduction therewith, thereby bringing the switch into conduction.
The band-like contacts may extend radially with respect to a center of the first contact, or the band-like contacts may extend into fan-like shape with respect to a center of the first contact.
The switch portion comprises the first contact, the one or more second contacts surrounding the first contact, and the pan-like diaphragm comprising a conductor, the second contacts are provided with one or more band-like contacts extending to the opposite side from the first contact, an outer periphery of the pan-like diaphragm is placed on the band-like contacts extending from the second contacts and brought into conduction with the band-like contacts, a center of the pan-like diaphragm is pushed down and bent, the center of the pan-like diaphragm is brought into contact with the first contact and into conduction therewith, thereby bringing the switch into conduction. Therefore, there is a merit that switch can be brought into conduction even if the second contacts do not correspond to the entire portion of the outer periphery of the diaphragm.
Further, if the band-like contacts extend radially with respect to a center of the first contact, there is a merit that a larger number of band-like contacts having smaller width can be disposed.
Further, if the band-like contacts extends into fan-like shape with respect to a center of the first contact, there is a merit that the area of the metal pattern portion of the second contact becomes wider as separating from the center of the first contact.